Handheld devices, including Personal Digital Assistants (PDAs) and cellular telephones, offer connectivity to the Internet and permit access to documents available over the Internet. Wireless Application Protocol (WAP) is a standard for providing cellular phones, PDAs, pagers and other handheld devices with secure access to web pages. WAP features the Wireless Markup Language (WML), which generally serves as a medium for translating web-based HTML content into a format that accommodates small form factor displays and key sets found on conventional handheld devices. WML also allows handheld device manufacturers to include microbrowsers in their products that accept WML input from a WAP-based system across vast regions of the world.
The proliferation of wireless PDAs has also created a popular means for handheld Internet access. However, presenting IP-based content, and other content developed for display on large form factor devices (e.g., PC monitors), on small form factor screens of handheld devices has, in the past, been problematic. Two primary methods of presenting such content to handheld devices have been employed.
The first such method can be termed “fixed mapping”. Fixed mapping typically involves rewriting an existing document, such as an HTML-based web page, to conform to a specific standard, such as WAP, J-PHONE, or i-Mode, or to a small display device. A web server must then maintain the rewritten web site as a separate site with its own URL in addition to the original document. As new content is added to the original document, a web site operator must manually trim, edit, and condense the new content by rewriting the new content into a format that will accommodate the interface parameters of handheld devices. This method is limited in that considerable time and expense are typically required to maintain the two web sites in parallel. Further, the manual editing of the rewritten web site can be time-consuming, burdensome, and expensive.
The second method may be termed “transcoding”. Transcoding typically involves the use of software that takes the entire content of a web site as input, converts the entire content into a format of a specific handheld wireless standard for transmission to handheld devices. The entire content, as formatted according to a handheld wireless standard, is then transmitted to the handheld device. This conversion may be performed “on-the-fly” (i.e., automatically in real time) or may be performed manually.
Transcoding has the advantage of reducing the investment to reach wireless markets since it leverages existing web sites. From a user standpoint, transcoding is desirable in that it preserves all the text-based information from the originating site. For large volumes of text, however, using this approach may overwhelm the handheld device user with large volumes of text to be viewed on a small form factor display. Further, the unorganized transcoded content makes changes or modifications to the wirelessly enabled web site more difficult for the web site operator.
In addition, many wireless handheld devices have limited bandwidth. Thus, downloading an entire web page designed for viewing on a large form factor device at data rates common to handheld wireless devices may require large download times. These large download times may be burdensome to the user who must wait while the entire web page downloads, even though the user may only desire to view a portion of the web page. Further, these large download times may be expensive for users who pay for wireless service based on the amount of time or the number of packets downloaded. For example, service plans are time-based or packet-based. These service plans charge on either the time connected or number of packets received, respectively, Thus, large downloads under these service plans will be more expensive than smaller downloads.
Additional background details are disclosed in U.S. Pat. No. 6,336,124, the disclosure of which is hereby incorporated by reference.